Multi-mode multi-band self-realigning power amplifier

ABSTRACT

A power amplifier (PA) system is provided for multi-mode multi-band operations. The PA system includes one or more amplifying modules, each amplifying module including one or more banks, each bank comprising one or more transistors; and a plurality of matching modules, each matching module being configured to be adjusted to provide impedances corresponding to frequency bands and conditions. A controller dynamically controls an input terminal of each bank and adjusts the matching modules to provide a signal path to meet specifications on properties associated with signals during each time interval.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 14/953,175, filed Nov.27, 2015, titled “Multi-Mode Multi-Band Self-Realigning PowerAmplifier;” which is a divisional of U.S. Ser. No. 13/557,173, filedJul. 24, 2012 (now U.S. Pat. No. 9,231,536, issued Jan. 5, 2016), titled“Multi-Mode Multi-Band Self-Realigning Power Amplifier;” which furtherclaims benefit of priority with U.S. Provisional Ser. No. 61/511,114,filed Jul. 24, 2011, titled “Multi-Mode Multi-Band Self-Realigning PowerAmplifier;” the contents of each of which are hereby incorporated byreference.

FIELD OF INVENTION

The present invention relates to power amplifier systems designed formulti-mode multi-band operations and capable of readjusting signalproperties in response to perturbations.

BACKGROUND OF THE INVENTION

Frequency bands and modes associated with various protocols arespecified per industry standards for cell phone and mobile deviceapplications, WiFi applications, WiMax applications and other wirelesscommunication applications, and the number of specified bands and modesis increasing as the demand pushes. Examples of the frequency bands andmodes for cell phone and mobile device applications are: the cellularband (824-960 MHz) which includes two bands, CDMA (824-894 MHz) and GSM(880-960 MHz) bands; and the PCS/DCS band (1710-2170 MHz) which includesthree bands, DCS (1710-1880 MHz), PCS (1850-1990 MHz) and AWS/WCDMA(2110-2170 MHz) bands. Examples for uplink include the frequency rangesof DCS (1710-1785 MHz) and PCS (1850-1910 MHz). Examples for downlinkinclude the frequency ranges of DOCS (1805-1880 MHz) and PCS (1930-1990MHz). Examples of frequency bands for WiFi applications include twobands: one ranging from 2.4 to 2.48 GHz, and the other ranging from 5.15GHz to 5.835 GHz. The frequency bands for WiMax applications involvethree bands: 2.3-2.4 GHZ, 2.5-2.7 GHZ, and 3.5-3.8 GHz. Use of frequencybands and modes is regulated worldwide and varies from country tocountry. For example, for uplink, Japan uses CDMA (915-925 MHz) andSouth Korea uses CDMA (1750-1780 MHz). In this document, “modes” referto WiFi, WiMax, LTE, WCDMA, CDMA, CDMA2000, GSM, and so on; and “bands”or “frequency bands” refer to frequency ranges (700-900 MHz), (1.7-2GHz), (2.4-2.6 GHz), (4.8-5 GHz), and so on.

Power amplifiers (PAs) are designed to amplify power of radio frequency(RF) signals and are widely used in various RF circuits and devices. Inmodern communication systems, it is generally preferred that PAs providehigh linearity and high efficiency in order to achieve a certainperformance level. High efficiency is important for power loss reductionto prolong the battery lifetime of handsets, for example. High linearityis important to maintain the integrity of the signal with minimaldistortion. Specifications on PA performances are defined for individualmodes and bands per industry standards. These specifications involveproperties associated with output signals, such as output power, poweradded efficiency (PAE), error vector magnitude (EVM), adjacent channelleakage ratio (ACLR) and other performance parameters. PAE is defined asthe ratio of the difference between output power and input power to theDC power consumed. The curve showing output power versus input powerindicates linearity. Linearity may also be evaluated by EVM, which is ameasure of how far the points are from the ideal lattice points,expressed as a percentage. Generally, an EVM diagram illustrates thatthe fixed lattice points correspond to non-distortion of the signalforms and the distortions are quantized by the deviations from thelattice points. Thus, as linearity improves, the EVM value decreases.The EVM value of 0% corresponds to non-distortion, that is, the outputsignal from the PA has a perfect copy of the input signal, therebygiving rise to ideal linearity. The linearity specification in terms ofEVM is 3% for LTE and WiFi, for example. ACLR is another performancemeasure for linearity and is specified for CDMA, WCDMA, LTE and WiMAX.It is defined as the ratio of the integrated signal power in theadjacent channel to the integrated signal power in the main channel.ACLR is also referred to as adjacent channel power ratio (ACPR).Transistors are used for the power amplification purposes and may beintegrated on a chip. These transistor may be a Metal SemiconductorField Effect Transistor (MESFET), a Pseudomorphic High Electron MobilityTransistor (pHEMT), a Heterojunction Bipolar Transistor (HBT) or ofother suitable technologies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a conventional PA structure.

FIG. 2 illustrates another example of a conventional PA structure.

FIG. 3 illustrates an exemplary architecture of a conventionalcommunication system.

FIG. 4 illustrates an exemplary architecture of a communication system,incorporating a PA system that can handle multiple modes and multiplebands.

FIG. 5 is a block diagram illustrating an exemplary bidirectionalcontrol.

FIG. 6 illustrates a PA system that allows for the dynamictuning/retuning scheme for multi-mode and multi-band operations.

FIG. 7 shows three tables, Table 1, Table 2 and Table 3: Table 1tabulates examples of industry specifications for some modes; Table 2tabulates examples of possible different frequency bands; Table 3tabulates exemplary numbers of transistors in the banks.

FIG. 8 illustrates a process flow of an algorithm to operate the PAsystem.

FIG. 9 illustrates a first example of the matching module that can beimplemented in the PA system of FIG. 6.

FIG. 10 illustrates an exemplary PA system including the first exampleof the matching module of FIG. 9.

FIG. 11 illustrates a second example of the matching module that can beimplemented in the PA system of FIG. 6.

FIG. 12 illustrates a third example of the matching module that can beimplemented in the PA system of FIG. 6.

FIG. 13 plots exemplary phase-versus-frequency curves for a RH structure(dotted line), a LH structure (dotted-dashed line) and a CRLH structure(solid line).

FIG. 14 illustrates a fourth example of the matching module that can beimplemented in the PA system of FIG. 6.

FIG. 15 illustrates a fifth example of the matching module that can beimplemented in the PA system of FIG. 6.

FIG. 16 illustrates a sixth example of the matching module that can beimplemented in the PA system of FIG. 6.

FIG. 17 illustrates a first example of a Tx system where two or more Txmodules are coupled to multiple input ports, respectively, and coupledto multiple antennas, respectively.

FIG. 18 illustrates a second example of a Tx system where two or more Txmodules are coupled to multiple input ports, respectively, and coupledto a single antenna.

DETAILED DESCRIPTION

As communication systems need to support worldwide protocols withdifferent bands and different modes, conventional single-mode,single-band PA architectures may pose rigidity with littlereconfiguration possibility and yet occupy a large circuit estate.Furthermore, a communication system with an air interface tends to beaffected by changes in conditions such as the presence of a human hand,a head, a metal object and other interference-causing objects placed inthe vicinity of an antenna. In such cases, for example, a change inimpedance may detune the antenna that can affect the system load; thecommunication band may be shifted due to the detuning. A conventionalsystem with passive antennas generally is not capable of readjusting itsfunctionality to recover optimum performances. A tunable antenna, forexample, can be used to alleviate the perturbed properties bycontrolling the beam, frequency response, impedance and other antennacharacteristics so as to recover the original optimum performances. See,for example, U.S. Pat. Nos. 6,900,773, 7,830,320 and 7,911,402, whichdescribe examples of active tunable antennas. Another way to recover theoptimum performances may involve readjusting components and modules inthe communication system based on the detuning information from theantenna through, for example, a bidirectional control line. Both thetunable antenna and the adjustable components and modules may be usedfor increased flexibility.

This document describes implementations of a PA system that can handlemultiple modes and multiple bands to replace a conventional PAarchitecture comprised of single-band, single-mode PAs, and at the sametime is capable of adjusting frequency, impedance, output power, andother signal properties. As described later in this document, theseadvanced PA features can be achieved by incorporating banks oftransistors with different sizes in combination with adjustable matchingmodules, and dynamically changing the banks and the matching modulesbased on the time-varying information about the signals and conditions.

In a conventional communication system, each PA is typically designed tooperate for a specific frequency band and for a chosen mode. This schemeprovides the ease of designing a narrowband system or a module includingmultiple narrowband signal paths, as shown in the example below.

FIG. 1 illustrates an example of a conventional PA structure, whereinmatching networks and transistors are configured to operate forrespective frequency bands, each with a single mode. This exampleschematically shows a PA structure adapted for three frequency bands,Band1, Band2, and Band3, having corresponding three different signalpaths. Each path carries signals in the specified band with thespecified mode. The signals paths for these Band1, Band2 and Band3 arecoupled to respective inputs and outputs, i.e., Input @Band1 andOutput@Band1, Input@Band2 and Output@Band2, and Input@Band3 andOutput@Band3, respectively. Multiple transistors may be integrated on afirst chip 104 for Band1, a second chip 108 for Band2, and a third chip120 for Band3, using a suitable technology as mentioned earlier. Thisexample schematically shows a case of integrating three transistors,labeled Transistor1, Transistor2 and Transistor3 on each chip, with thematching networks for each band attached externally to the chip. Here a“Transistor” may be a group of individual transistors coupled together.An input matching network IMN@Band1, an output matching networkOMN@Band1, and two inter-matching networks InMN1@Band1 and InMN2@Band1are configured for the Band1 signal path. Similarly, an input matchingnetwork, an output matching network and two inter-matching networks fora different band are configured for the corresponding signal path. Thefirst inter-matching network InMN1 is coupled between Transistor1 andTransistor2, and the second inter-matching network InMN2 is coupledbetween Transistor2 and Transistor3 for each signal path. Transistor1can be used as a driver, followed by a two-stage power amplificationrealized by Transistor2 and Transistor3.

A power amplifier is one of the most power hungry components in radiofrequency (RF) and other communication systems. Accordingly it isimportant not only to have PAs with high efficiency but also when a PAis not used to turn it off so as to consume less power without affectingthe rest of the system. The power consumption and the chip area can besomewhat reduced by including switches and transistors that can handlesignals in multiple bands, as shown in the following example.

FIG. 2 illustrates another example of a conventional PA structure,wherein matching networks are configured to turn on and off depending onsignal frequencies. This example schematically shows a PA structureadapted for three frequency bands, Band1, Band2, and Band3 havingcorresponding three different signal paths. Each path carries signals inone of the bands in a single mode. These Band1, Band2 and Band3 signalpaths are coupled to a common input 201 and a common output 202.Multiple transistors may be integrated on a chip 204 using a suitabletechnology as mentioned earlier. This example schematically shows a caseof integrating three transistors, labeled Transistor1, Transistor2 andTransistor3 on the chip 204, with the matching networks attachedexternally to the chip. Here, again, a “Transistor” may be a group ofindividual transistors coupled together. Less chip area may be requiredin this configuration than in the configuration of FIG. 1 by includingtransistors in the chip 204 that are capable of handling signals inmultiple frequency bands. Input matching networks for the three bandsIMN@Band1, IMN@Band2 and IMN@Band3 are coupled in parallel, having acommon input point where a switch 208 is placed and a common outputpoint where a switch 212 is placed. First inter-matching networks forthe three bands InMN1@Band1, InMN1@Band2 and InMN1@Band3 are coupled inparallel, having a common input point where a switch 216 is placed and acommon output point where a switch 220 is placed. Second inter-matchingnetworks for the three bands InMN2@Band1, InMN2@Band2 and InMN2@Band3are coupled in parallel, having a common input point where a switch 224is placed and a common output point where a switch 228 is placed. Outputmatching networks for the three bands OMN@Band1, OMN@Band2 and OMN@Band3are coupled in parallel, having a common input point where a switch 232is placed and a common output point where a switch 236 is placed. Thefirst paralleled set of inter-matching network InMN1 @Band1, InMN1@Band2and InMN1@Band3 is coupled between Transistor1 and Transistor2, and thesecond paralleled set of inter-matching networks InMN2@Band1,InMN2@Band2 and InMN2@Band3 is coupled between Transistor2 andTransistor3. Transistor1 can be used as a driver, followed by atwo-stage power amplification realized by Transistor2 and Transistor3.

The switches incorporated as in the configuration of FIG. 2 may becontrolled by a controller. For example, when the signal frequency isspecified to be in Band1, the switches 208, 212, 216, 220, 224, 228 and232 may be controlled to turn on and connect the corresponding signalpath having IMN@Band1, InMN1@Band1, InMN2@Band1 and OMN@Band1, whileturning off to disconnect the other paths. A variation to the switchableconfiguration may include only one paralleled set of inter-matchingnetworks coupled between two transistors in the chip, adaptable for lowpower applications.

FIG. 3 illustrates an exemplary architecture of a conventionalcommunication system including an RF front end module 300 coupled to anantenna 304 and a transceiver 308. Transmit (Tx) signals are inputtedfrom a Tx input 312 of the transceiver 308, receive (Rx) signals areoutputted from an Rx output 313 of the transceiver 308, and thesesignals are processed by various components and modules configuredtherein. In this example, the Tx signals have five frequency bands, eachwith a single mode, e.g., DCS (1805-1880 MHz), PCS (1930-1990 MHz), WiFi(2.4 to 2.48 GHz), etc., and are outputted from respective Tx ports 314of the transceiver 308. Also in this example, the Rx signals have sixfrequency bands, three of which have two sub-bands, and the Rx signalsin the total of nine bands are inputted to respective Rx ports 315 ofthe transceiver 308. Generally, Tx signals are lower in frequency thanRx signals within the same nominal band, forming a Tx band lower than anRx band within the same nominal band. The antenna 304 is coupled to aswitchplexer 318 to switch between transmit and receive as well as amongdifferent bands and modes. Each PA in this example operates for a singleband and a single mode, as in the configuration of FIG. 1. The Txsignals coming out from the lower three ports of the Tx ports 314 areamplified by PAs 320, 321, and 322, respectively, and filtered throughduplexers 324, 325, 326, respectively, to reach the antenna 304 throughthe switchplexer 318 that turns on and connects the corresponding paths.On the other hand, the Rx signals in these three bands are filteredthrough the duplexers 324, 325 and 326, respectively, and then sent tothe lower three ports of the Rx ports 315, respectively. This example inFIG. 3 shows that PAs to amplify the Tx signals coming out of the uppertwo ports of the Tx ports 314 are integrated on a same chip 327. Thisexample shows that the amplified Tx signals in the two bands reach theswitchplexer 318 without a duplexer. Also shown in FIG. 3 are filters328, 329 and 330, which can receive the Rx signals in three differentmodes, respectively. In this example, each of the filters 328, 329 and330 is configured to have a differential output to send the splitsignals to the Rx ports 315. Generally low noise amplifiers (LNAs) areincluded in the first stage in a transceiver to receive signals withminimal noise to increase sensitivity and sensibility. A differentialLNA provides a better noise figure than a single-ended because of itsability to reject the common-mode noise.

FIG. 4 illustrates an exemplary architecture of a communication system,incorporating a PA system that can handle multiple modes and multiplebands to replace a conventional PA architecture comprised ofsingle-band, single-mode PAs, and at the same time is capable ofadjusting frequency, impedance, output power and other properties whichonce have been perturbed due to changes in conditions. Such a PA systemis thus termed a multi-mode multi-band self-realigning PA system in thisdocument. This communication system includes an RF front end module 400coupled to an antenna 404 and a transceiver 408. A PA system 412 isconfigured to provide functions as the multi-mode multi-bandself-realigning PA system, included in the RF front end module 400, anddesigned to amplify Tx signals and send the amplified signals to a Txfilter system 416. In the present filter configuration, Rx filters andTx filters are separated instead of forming duplexers, having the Txfilter system 416 and an Rx filter system 417. As in the conventionalcase of FIG. 3, the Tx signals are inputted from a Tx input port 420coupled to the transceiver 408, Rx signals are outputted from an Rxoutput 421 coupled to the transceiver 408. The Tx signals received atthe Tx input port 421 are processed by a Tx section having componentsand modules coupled to the Tx paths in the system, and transmitted outfrom the antenna 404; Rx signals are received by the antenna 404 andprocessed by an Rx section having components and modules coupled to theRx paths in the system, and outputted from the Rx output port 421. Theantenna 404 is configured for both transmit and receive functions fordifferent modes and bands. The antenna 404 in this example is coupled toa switchplexer 428, which is coupled to the Tx section and the Rxsection to switch between the Tx section and the Rx section as well asamong different bands and modes. Specifically, during a given timeinterval, the antenna 404 is configured to either transmit or receivesignals in a mode selected from the multiple modes and in a frequencyband selected from the multiple bands. For example, the Tx signals canbe in multiple different frequency bands, each with a single mode, suchas mode-and-band combinations of DCS (1805-1880 MHz), PCS (1930-1990MHz), WiFi (2.4 to 2.48 GHz), etc., and the Tx signals in one of thesecombinations are sent through a Tx port 425 of the transceiver 408during the given time interval. Selection of the mode and the band canvary with time; thus, the Tx port 425 sends Tx signals in a differentmode and a different band during a different time interval. As in theprevious example of FIG. 3, shown in FIG. 4 are filters 432, 433 and434, which receive the Rx signals in three different modes,respectively. In this example, each of the filters 432, 433 and 434 isconfigured to have a differential output to send the split signals tothe Rx ports 424. Generally LNAs are included in the first stage in atransceiver to receive signals with minimal noise to increasesensitivity and sensibility. A differential LNA provides a better noisefigure than a single-ended because of its ability to reject thecommon-mode noise.

The antenna 404 may be a passive antenna or a tunable antenna. The useof a tunable antenna in combination with the multi-band multi-modeself-realigning PA system may provide increased flexibility inreadjusting signal properties as compared to the case of using only sucha PA system or a tunable antenna.

Algorithms to control various components are included in a controller436, which is coupled to the Tx section to adjust properties associatedwith the Tx signals. The controller 436 in this example is coupled tothe PA system 412, the antenna 404, the transceiver 416, and theswitchplexer 428 through a bidirectional control line 440. Such controlconnections can be made to other components in the system and/orcomponents inside of a subsystem or a module. The bidirectional controlcan be realized, for example, by using an interface specified by theMIPI Alliance. See, for example, a white paper entitled “TuningTechnology: Key Element to Lower Operating Costs While ImprovingWireless Network Performance,” released on Feb. 8, 2011, by IWPC(International Wireless Industry Consortium). The bidirectional controlline 440 can be a conventional bus, wirelessly-connected transmission orother suitable forms. In the communication system of FIG. 4, thecontroller 436 may be configured to obtain information about the Txsignals from a user selection, a base station and other commandinglocations or systems and accordingly control the PA system 412 and othercomponents to select the optimum configuration corresponding to the modeand the band of the Tx signals to meet specifications on propertiesassociated with the Tx signals. Further, the controller 436 controls thePA system and other components variably with time as the informationvaries to provide the optimum configuration during each time interval.Furthermore, when the antenna 404 gets detuned by changes in conditions,for example, by the presence of a head, a hand or otherinterference-causing objects in the proximity of the antenna 404, thecontroller 436 may obtain the detuning information from the antenna 404and accordingly control the PA system 412 and other components toreadjust the affected parameters. For example, the change in impedanceand/or the shift in band frequency may be sensed by the antenna 404 andretuned to the optimum state by adjusting the PA system 412 and the Txfilter system 416.

For the bidirectional control to work, various components and modules inthe communication system as well as components and modules coupledexternally to the communication system need to communicate with eachother through a bidirectional control line such as 440 of FIG. 4. Thebidirectional control may be implemented though a suitable interfacescheme such as the one specified by the MIPI Alliances mentionedearlier. FIG. 5 is a block diagram illustrating an exemplarybidirectional control, wherein a bidirectional control line 500 is usedto couple an antenna, a filter system, a PA system, low-noise filter(LNA) system, an IF block, a back-end, a baseband, a CPU and anApplications CPU (Apps CPU) through interfaces 504, 505, 506, 507, 508,509, 510, 511 and 512, respectively implemented. The filter system andthe PA system are included in the RF front end module, and the LNAsystem, the IF Block and the back-end may be included in thetransceiver. Algorithms controlling these components and modules can beincluded in the controller that may be placed in the baseband 516, theCPU 517 or the Apps CPU 518.

The present bidirectional control scheme can be extended to amultiple-input multiple-output (MIMO) system, wherein the communicationsystems such as in FIG. 4 are coupled in parallel with individualinputs/outputs, each communication system handling multiple modes andmultiple bands. The spatial placement and orientation of antennas maydiffer from one another in the MIMO system, giving rise to non-uniformdetuning effects. The antennas in the MIMO system tend to interact witheach other due to the electromagnetic proximity effects (couplingeffects). For example, these antennas have different loadings so thatexternal effects have different loading effects on different antennasprimarily because of different coupling effects between antennas. Thecontroller may be configured to couple to the multiple PA systems, themultiple filter systems and the multiple antennas through abidirectional control line and interfaces in order to retune theantennas one by one by taking the coupling effects into consideration.Therefore, the dynamic retuning becomes particularly important for theMIMO system.

FIG. 6 illustrates a PA system that allows for the dynamictuning/retuning scheme for multi-mode and multi-band operations. The PAsystem is configured to include multiple banks of transistors withdifferent sizes in each power amplifying module as well as multiplematching modules that are designed to provide the optimum impedance foreach of multiple frequency bands, allowing to dynamically change thesignal path by selecting an optimum series of banks and adjusting thematching modules. Specifically, the PA system of FIG. 6 includes thefirst matching module 604, the second matching module 605, the thirdmatching module 606 . . . and the (k+1)th matching module 607, and thefirst amplifying module 608, the second amplifying module 609 . . . andthe kth amplifying module 610. Each matching module is configured to beadjustable to provide the optimum impedance for a specified frequencyband and given conditions. Each amplifying module includes one or morebanks, each bank including one or more transistors connected to have acommon input terminal such as a gate or a base. These banks in theamplifying module are sized differently to amplify power of signals todifferent predetermined levels. Generally, the larger the size is, thelarger the power amplifying level is. Thus, one or more banks in theamplifying module can provide one or more different power levels. Thenumber of banks in each amplifying module may vary from module to moduleas denoted by m₁, m₂ . . . and m_(k) in the figure. The number ofmatching modules, (k+1), is one more than the number of amplifyingmodules, k, and they are coupled alternately in series having the firstmatching module 604 coupled to an input port 624 and the (k+1)thmatching module 607 coupled to an output port 625. The first matchingmodule 604 may serve as an input matching network, and the firstamplifying module may provide driver transistors. In cases where theoutput power of output signals varies, the number of amplifying modulescan also vary to provide variable number of amplifying stages. Theoutput signals can thus be outputted at an earlier stage, such as takingan output line 626, 627 or 628 to the output port 625, by turning offthe subsequent amplifying modules and matching modules.

A controller 630 can be configured to control the matching modules, thepower amplifying modules, and components therein including the inputterminal such as a gate or a base of each bank. A bidirectional controlline 634 can be configured to connect the controller 630, the matchingmodules 604, 605, . . . and 607 and components therein, the poweramplifying modules 608, 609, . . . and 610 and components therein, anantenna and other components or modules. The controller 630 can beconfigured also to receive information about output signals andconditions via the bidirectional control line 634. Such information maybe received from a user selection, a base station, or other commandinglocations or systems. Such information may also be obtained from theantenna coupled to a communication system where the PA system resides.The information can vary with time as the signals and conditions vary.Based on the information the controller 630 can adjust each of thematching modules 604-607 to provide the optimum impedance for thespecified frequency band and the given conditions during a given timeinterval. Furthermore, based on the information the controller 630 cancontrol the input terminal (a gate or a base) of each bank to turn on aseries of banks, by selecting one bank from each amplifying module in apredetermined series to provide an optimum power amplifying level forthe mode and the frequency band specified during the given timeinterval. As a result, these adjusted matching modules and the selectedbanks are coupled alternately in series to provide an optimum signalpath having the first matching module 604 coupled to the input port 624and also having a last matching module, which receives signals from thelast bank in the series, coupled to the output port 625. Since theinformation on the signals and conditions can vary with time, theadjustment of the matching modules and the selection of banks can varywith time to meet specifications of properties of the output signalsduring each time interval. That is, the controller 630 can adjust thematching modules and control the input terminals of banks variably withtime according to the time-varying information. The number of selectedbanks in the series can be less than or equal to the total number ofamplifying modules, k; and correspondingly the number of matchingmodules in the optimum signal path can be less than or equal to thetotal number of sets of MNs, (k+1). The output signals may thus beoutputted at an earlier stage, such as taking the output line 626, 627or 628 to the output port 625. For example, each mode needs a certainoutput power to meet the industry specifications. Therefore, theselection of banks for the optimum series is made to meet the outputpower requirement for the selected mode and band. Accordingly, if thepower level is allowed to be lower, such as in the WiFi mode, the numberof banks in the optimum series can be less than the total number ofamplifying modules, k. In any case, the sequence of the optimum signalpath having the adjusted matching modules and the selected banks has thefirst matching module serving as an input matching network coupled tothe input port 624 and the last matching module serving as an outputmatching network coupled to the output port 625.

Industry specifications for each mode are published in terms of not onlyoutput power, but also efficiency, linearity and other properties. Theoptimum series of banks and matching modules for each mode and band maybe predetermined to meet the industry specifications based on nominalconditions. The controller 630 can then be configured to control thematching modules and the input terminals (gates/bases) of the banks todynamically change the signal path according to the time-varyinginformation it receives. The present PA system of FIG. 6 is thus capableof dynamically providing an optimum signal path by selecting a series ofbanks, adjusting each of the matching modules and coupling themalternately in series to meet the specified properties of outputsignals. Such flexibility in the present scheme is provided by havingthe differently sized banks and the matching modules designed to beadjustable.

When the antenna gets detuned by perturbations such as the presence of ahead, a hand or other interference-causing objects, the controller 630obtains information on the perturbed output signals from the antenna andcontrol the modules and components in the PA system to readjust theaffected parameters. For example, the change in impedance may be sensedby the antenna, and the information is sent to the controller 630 viathe bidirectional control line 634. The controller 630 then adjusts thematching modules to recover the impedance. For another example, thechange in frequency of the output signals may be sensed by the antenna,and the information is sent to the controller 630. The controller thenadjusts the matching modules to recover the frequency band and alsocontrols the input terminals of the banks to turn on a series of banksto recover the power amplifying level for the frequency band.Perturbations to nominal conditions include a distance to a basestation. For example, when the system is close to the base station andthe output power does not have to be high, the PA system does not haveto amplify the power level significantly. Accordingly, the controller630 controls the input terminals of the banks to turn on less number ofbanks in the series than when the system is in a nominal range from thebase station, thereby outputting less output power.

FIG. 7 shows three tables, Table 1, Table 2 and Table 3. Table 1tabulates examples of industry specifications for some modes such asWiFi, WiMax, LTE, WCDMA, GSM, CDMA, CDMA 2000 and EDGE. Thespecifications are established for properties of output signals in eachmode using characteristic parameters such as output power (Pout),efficiency (PAE), and linearity (ACLR, EVM), etc. Each mode may have oneor more frequency bands. Table 2 tabulates examples of possibledifferent frequency bands.

Banks of transistors in a PA system can be sized differently to providedifferent power levels, linearity and other properties. The size of abank is typically determined by the number of transistors, the number offingers of an input terminal (a gate or a base) of the bank, and overalllength and width of the transistor. These transistors may be a MetalSemiconductor Field Effect Transistor (MESFET), a Pseudomorphic HighElectron Mobility Transistor (pHEMT), a Heterojunction BipolarTransistor (HBT) or of other suitable technologies. Table 3 in FIG. 7tabulates exemplary numbers of transistors in the banks by fixing theother parameters as a measure representing the sizes of prefabricatedbanks. Table 3 shows an example in which the first amplifying module hasthree banks with the numbers of transistors 4, 6 and 8, respectively,the second amplifying module has two banks with the number oftransistors 12 and 16, and the third amplifying module has two bankswith the number of transistors 16 and 20, respectively. Assuming nominalloads and other nominal conditions, the optimum series of banks can bepredetermined for each combination of a mode and a band to meet thespecifications. That is, the optimum series of banks for the WiFi(2.3-2.5 GHz) has the bank of 4 transistors selected from the firstamplifying module and the banks in the subsequent amplifying modules areturned off; the optimum series of banks for the WCDMA (700-900 MHz) andWCDMA (1.7-2 GHz) has the bank of 6 transistors selected from the firstamplifying module, the bank of 12 transistors selected from the secondamplifying module and the banks in the subsequent amplifying modules areturned off; the optimum series of banks for the GSM (700-900 MHz) hasthe bank of 8 transistors selected from the first amplifying module, thebank of 16 transistors selected from the second amplifying module andthe bank of 20 transistors selected from the third amplifying module;and the optimum series of banks for the GSM (1.7-2 GHz) has the bank of6 transistors selected from the first amplifying module, the bank of 12transistors selected from the second amplifying module and the bank of16 transistors selected from the third amplifying module.

FIG. 8 illustrates a process flow of an algorithm to operate the PAsystem. In the first step 804, the system selects the combination of afrequency band and a mode depending on information from, e.g., a userselection, a base station, or other commanding locations or systems. Inthe next step 808, the system obtains specifications for the selectedband and mode in terms of output power, efficiency, and linearity andother properties. These specifications can be tabulated in terms ofPout, PAE, ACPR, EVM, etc. in a lookup table format, as in Tables 1 and2, for example, which may be loaded onto the controller beforehand.Assuming certain nominal conditions, such as loads and a distance to thebase station, in the next step 812, the system provides the optimumsignal path by selecting banks from the amplifying modules and adjustingthe matching modules. In the next step 816, the system checks if adifferent combination of a mode and a band is specified, for example, bya user entering a foreign country that uses a different protocol forcommunications. If “Yes,” the system goes back to the initial step 804to select the new mode and the new band, and follow the same process. If“No,” the system still keeps the optimum signal path for the originallyselected mode and band, but the system checks if there are anyperturbations caused by changes in conditions, such as a change inoutput power due to the change in distance to the base station,frequency shift and/or impedance change caused by the presence of aninterference-causing object in the proximity of the antenna, and so on.If “Yes,” the system goes back to the step 812 to seek for an optimumsignal path by selecting banks from the amplifying modules and adjustingthe matching modules. If there is no perturbation, the system keeps theoptimum signal path previously selected as in the step 824, but keepsmonitoring if there are any perturbations or changes in selection of amode and a band.

FIG. 9 illustrates a first example of the matching module that can beimplemented in the PA system of FIG. 6. This matching module includesmultiple matching networks (MNs) 904, 905 . . . 906, denoted by MN1, MN2. . . , and MNn, respectively in the figure, coupled in parallel with afirst common end coupled to a first switch 909 and a second common endcoupled to a second switch 909. The multiple matching networks (MNs) areconfigured to provide an impedance value suitable for each of thefrequency bands. The controller, such as the controller 630 in FIG. 6,can control the switches 908 and 909 to select one of the MNs designedto provide the optimum impedance for a specified frequency band during agiven time interval. Each of the MNs may include one or more tunablecomponents that can be controlled by the controller to further adjustthe impedance. When the antenna in the communication system in which thePA system resides senses the deviation of impedance from a nominalvalue, for example, 50Ω, the controller receives the information fromthe antenna through the bidirectional control line, such as thebidirectional control line 634 of FIG. 6. Based on the information thecontroller can control the tunable components to adjust the impedance.

FIG. 10 illustrates an exemplary PA system including the first exampleof the matching module of FIG. 9. This PA system is configured toprovide the optimum signal path for WiFi (2.3-5 GHz), WCDMA (700-900MHz), WCDMA (1.7-2 GHz), GSM (200-900 MHz) and GSM (2.7-2 GHz) undernominal conditions, such as nominal loads and a nominal distance to abase station, as exemplified in Table 3. This PA system includes thefirst matching module 1004, the second matching module 1005, the thirdmatching module 1006 and the fourth matching module 1007, and the firstamplifying module 1008, the second matching module 1009 and the thirdmatching module 1010. These matching modules and amplifying modules arecoupled alternately in series having the first matching module 1004being coupled to an input port 1020 and the fourth matching module 1007being coupled to an output port 1021. The matching modules 1004 includesthree MNs 1024, 1025 and 1026 designed for three frequency bands(700-900 MHz), (1.7-2 GHz) and (2.3-2.5 GHz), respectively. The firstamplifying module 1008 includes three banks 1028, 1029 and 1030 sizedwith 4 transistors, 6 transistors and 8 transistors, respectively. Thesecond matching module 1005 includes three MNs 1032, 1033 and 1034designed for three frequency bands (700-900 MHz), (1.7-2 GHz) and(2.3-2.5 GHz), respectively. The second amplifying module 1009 includestwo banks 1036 and 1037 sized with 12 transistors and 16 transistors,respectively, and optionally includes the third bank 1038 sized with 6transistors. The third matching module 1006 includes two MNs 1040 and1041 designed for two frequency bands (700-900 MHz) and (1.7-2 GHz),respectively, and optionally includes the third MN 1042 for thefrequency band (2.3-2.5 GHz). The third amplifying module 1010 includestwo banks 1044 and 1045 sized with 16 transistors and 20 transistors,respectively, and optionally includes the third bank 1046 sized with 8transistors. The fourth matching module 1007 includes two MNs 1048 and1049 designed for two frequency bands (700-900 MHz) and (1.7-2 GHz),respectively, and optionally includes the third MN 1050 for thefrequency band (2.3-2.5 GHz).

The controller 1060 is configured to receive information about outputsignals via a bidirectional control line 1064. Such information may bereceived from a user selection, a base station, or other commandinglocations or systems. Such information may also be obtained from anantenna coupled to the communication system where the PA system resides.The information can vary with time as the output signals vary. Based onthe information, the controller 1060 controls the switches 1012-1019 toturn on a series of MNs, by selecting one MN from each matching modulein a predetermined series to provide the optimum impedance for thefrequency band specified during the given time interval. Each of the MNsmay include one or more tunable components that can be controlled by thecontroller to further adjust the impedance. Furthermore, based on theinformation the controller 1060 controls the input terminal (a gate or abase) of each bank to turn on a series of banks, by selecting one bankfrom each amplifying module in a predetermined series to provide anoptimum power amplifying level for the mode and the frequency bandspecified during the given time interval. The selected MNs and theselected banks are coupled alternately in series to provide an optimumsignal path having the first MN coupled to the input port 1020 and thelast MN coupled to the output port 1021. According to Table 3, for theWiFi (2.3-2.5 GHz), the controller 1060 selects the MN 1026 with the(2.3-2.5 GHz) design from the first matching module 1004, the bank 1028with 4 transistors from the first amplifying module 1008, and the MN1034 with the (2.3-2.5 GHz) design from the second matching module 1005and coupled them alternately in series, thereby realizing the optimumpath for the WiFi (2.3-2.5 GHz) under nominal conditions. The WiFi(2.3-2.5 GHz) signals are sent to the output port 1021 from the switch1015. According to Table 3, for the WCMA, the controller 1060 selectsthe bank 1029 with 6 transistors from the first amplifying module 1008and the bank 1036 with 12 transistors from the second amplifying module1009 for both (700-900 MHz) and (1.7-2 GHz) bands. Further, thecontroller 1060 selects the MN 1024 with the (700-900 MHz) design fromthe first matching module 1004, the MN 1032 with the (700-900 MHz)design from the second matching module 1005 and the MN 1040 with the(700.900 MHz) design from the third matching module 1006 for the WCDMA(700-900 MHz); and the MN 1025 with the (1.7-2 GHz) design from thefirst matching module 1004, the MN 1033 with the (1.7-2 GHz) design fromthe second matching module 1005 and the MN 1041 with the (1.7-2 GHz)design from the third matching module 1006 for the WCDMA (1.7-2 GHz).The WCDMA signals are sent to the output port 1021 from the switch 1017.According to Table 3, for the GSM (700-900 MHz), the controller 1060selects the bank 1030 with 8 transistors from the first amplifyingmodule 1008, the bank 1037 with 16 transistors from the secondamplifying module 1009 and the bank 1045 with 20 transistors from thethird amplifying module 1010, the MN 1024 with the (700-900 MHz) designfrom the first matching module 1004, the MN 1032 with the (700-900 MHz)design from the second matching module 1005, the MN 1040 with the(700-900 MHz) design from the third matching module 1006, and the MN1048 with the (700-900 MHz) design from the fourth matching module 1007.According to Table 3, for the GSM (1.7-2 GHz), the controller 1060selects the bank 1029 with 6 transistors from the first amplifyingmodule 1008, the bank 1036 with 12 transistors from the secondamplifying module 1009 and the bank 1044 with 16 transistors from thethird amplifying module 1010, the MN 1025 with the (1.7-2 GHz) designfrom the first matching module 1004, the MN 1033 with the (1.7-2 GHz)design from the second matching module 1005, the MN 1041 with the (1.7-2GHz) design from the third matching module 1006, and the MN 1049 withthe (1.7-2 GHz) design from the fourth matching module 1007. The GSMsignals are sent to the output port 1021 from the switch 1019.

Information on perturbations from the nominal conditions can be detectedand sent to the controller 1060. The controller 1060 then controls thecomponents in the PA system to adjust the affected parameters to recoverthe specified properties of the output signals. For example, when thesystem is far away from the base station and more output power than thenominal condition is needed, the optional bank 1038 with 6 transistorsin the second amplifying module 1009 may be added in the series toincrease the power level for the WiFi (2.3-2.5 GHz). Correspondingly,the optional MN 1042 with the (2.3-2.5 GHz) design in the third matchingmodule 1006 may also be added as the output matching network to send theoutput signals from the switch 1017 to the output port 1021, instead offrom the switch 1015. Similarly, when the base station is close by andthe output power level is high, the signal path for the WCDMA may nothave to include the bank 1036 with 12 transistors in the secondamplifying module 1009, since the power amplification by the bank 1029with 6 transistors in the first amplifying module 1008 may be enough tomeet the specification. The controller 1060 thus turns off the bank 1036and disconnects the third matching module 1006 to shorten the signalpath and send the WCDMA output signals from the switch 1015, instead offrom the original switch 1017, to the output port 1021. Another exampleof perturbation is the change in impedance that can be detected by theantenna. Upon receiving the information, the controller 1060 can controlthe tunable components in the MNs already in the signal path to furtheradjust the impedance. Yet another example of perturbation is a frequencyshift as detected by the antenna. Upon receiving the information, thecontroller 1060 can control the switches and the input terminals(gates/bases) of the banks to provide the optimum path by selecting MNsand banks for the specified frequency band.

Instead of coupling multiple MNs designed for different frequency bandsin parallel to configure the matching module as in the previous case,tunable components may be used in the matching module to cover multiplefrequency bands as well as to adjust the impedance. FIG. 11 illustratesa second example of the matching module that can be implemented in thePA system of FIG. 6. Both frequency and impedance can be adjusted bythis tunable matching module. Such a tunable matching module isconfigured to include inductors and capacitors, wherein one or morecomponents can be tunable and can be controlled by the controller. Thecomponents, tunable or not, in the matching module can be configured inseries, in shunt, in a combination of both or in other suitable circuitconfigurations or topologies. Examples of tunable capacitors include avaractor, and examples of tunable inductors include a MEMS tunableinductor. The tunable matching module of FIG. 11 is one specific exampleof having two tunable capacitors 1112 and 1113 and two tunable inductors1116 and 1117 in the series-shunt configuration. The number ofcomponents as well as the circuit configuration or topology depends onthe design for targeted frequency and impedance ranges and other designconsiderations. The controller controls these tunable components todynamically provide the optimum impedance for the specified band and theconditions that can vary with time.

FIG. 12 illustrates a third example of the matching module that can beimplemented in the PA system of FIG. 6. The two end portions of thematching module, a first port 1201 and a second port 1202, are used toimplement the matching module in the PA system to have the first port1201 for inputting the signals and the second port 1202 for outputtingthe signals or to have the first port 1201 for outputting the signalsand the second port 1202 for inputting the signals. This matching moduleincludes a first set of multiple microstrips 1204, 1205 and 1206,denoted by MS1, MS2 and MS3 in the figure, respectively, which arecoupled in parallel, and a second set of multiple microstrips 1208, 1209and 1210, denoted by MS4, MS5 and MS6 in the figure, respectively, whichare coupled in series. Although three microstrips are used in each ofthe first set and the second set in this example, the number ofmicrostrips can be different depending on the number of frequency bands,size considerations and other factors. The first set is coupled inseries with the signal path by connecting one end of each of themisrostrips to the signal path and the other end of each of themicrostrips to a switch 1212. The three microstrips 1208, 1209 and 1210in the second set are coupled alternately in series with switches 1216and 1217 in between to form a shunt stub, which is coupled in shunt withthe signal path by having one end connected to the signal path and theother end 1220 being either ground or open.

The controller in the PA system can be configured to control theswitches 1212, 1216, 1217 and 1210. The switch 1212 is controlled toselect one of the microstrips 1204, 1205 and 1206 in the first setdepending on the frequency of the signal. The switches 1216 and 1217 arecontrolled to adjust the electrical length depending on the frequencyband of the signal. For example, the electrical length of L_(A) isprovided by selecting only the microstrip 1208, MS4; the electricallength of L_(B) is provided by selecting the microstrips 1208 and 1209,MS4 and MS5; and the electrical length of Le is provided by selectingthe microstrips 1208, 1209 and 1210, MS4, MS5 and MS6. Each of theseelectrical lengths is designed to provide a desired imaginary part ofimpedance for a specified band, and each of the microstrips 1204, 1205and 1206 in the first set is designed to provide a desired real part ofimpedance for a specified band. Impedance is related to the phase of asignal wave, which is a function of frequency. The imaginary part ofimpedance is related to the electrical length. Thus, the higher thefrequency is, the shorter the electrical length is. Impedance Z andphase ϕ are related by the following relationship:Z=Real(Z)+j Imaginary(Z)=exp(jϕ).  Eq. (1)

See for example, U.S. Pat. No. 7,839,236, entitled “Power Combiners andDividers Based on Composite Right and Left Handed MetamaterialStructures,” for the description of microstrip designs based on theimpedance transformation, the phase-versus-frequency relationship andother techniques. Thus, by selecting the combination of a microstripfrom the first set and one or more microstrips in a series from thesecond set, the desired impedance can be provided for the specified bandduring a given time interval. For example, for a band A with a centralfrequency of f_(A), the microstrip 1204, MS1, from the first set and themicrostrip 1208, MS4, from the second set can be selected to provide theoptimum impedance for the band A; for a band B with a central frequencyof f_(B), the microstrip 1205, MS2, from the first set and themicrostrips 1208 and 1209, i.e., MS4 and MS5, from the second set can beselected to provide the optimum impedance for the band B; and for a bandC with a central frequency of f_(C), the microstrip 1206, MS3, from thefirst set and the microstrips 1208, 1209 and 1210, i.e., MS4, MS5 andMS6, from the second set can be selected to provide the optimumimpedance for the band C. Here, the values of the frequencies are in theorder of f_(A)>f_(B)>f_(C) corresponding to L_(A)<L₈<L_(C). Furthermore,one or more tunable components may be included in each of themicrostrips. The comptroller can be configured to control the tunablecomponents to further adjust the impedance.

The phase-versus-frequency relationship differ significantly in a righthanded (RH) material, a left handed (LH) material and a composite rightand left handed (CRLH) material. RH materials are naturally occurringmaterials such as microstrips, whereas LH materials and CRLH materialsare called metamaterials that are artificially structured. Thepropagation of electromagnetic waves in RH materials obeys theright-hand rule for the (E, H, β) vector fields, where E is the electricfield, B is the magnetic field and β is the wave vector (or propagationconstant). LH materials have a negative index of reflection withsimultaneously negative permittivity and permeability, with the (E, H,β) following the left-hand rule. See, for example, Caloz and Itoh,“Electromagnetic Metamaterials: Transmission Line Theory and MicrowaveApplications,” John Wiley & Sons (2006). See also, for example, U.S.Pat. No. 7,839,236, entitled “Power Combiners and Dividers Based onComposite Right and Left Handed Metamaterial Structures,” for thedescription of CRLH designs based on the impedance transformation, thephase-versus-frequency relationship and other techniques.

FIG. 13 plots exemplary phase-versus-frequency curves for a RH structure(dotted line), a LH structure (dotted-dashed line) and a CRLH structure(solid line). The RH phase is linear in frequency and can take on onlynegative values; thus, the choice of a frequency-phase pair is limited.On the other hand, the CRLH phase is non-linear in frequency, and thephase spans to reach large values in both the positive and negativedirections. The curvature of the CRLH non-linear curve can be adjustedby designing the CRLH structure accordingly. Thus, two or more desiredfrequency-phase pairs can be selected from the same CRLH curve. As anexample, indicated in FIG. 13 are three different frequencies f₁, f₂ andf₃ corresponding to three different phases. These three pairs offrequency and phase can be obtained by designing the CRLH structure toexhibit the desired phase-versus-frequency curve. As shown in Eq. (1)above, the phase determines the impedance. Therefore, the non-linearphase-to-frequency characteristics of the CRLH structure can provideflexibility for obtaining the optimum impedance values for specifiedmultiple frequency bands, respectively. Furthermore, overall circuitsize can be reduced by using lumped elements to construct the CRLHportion instead of using conventional microstrips, which are RHmaterials.

FIG. 14 illustrates a fourth example of the matching module that can beimplemented in the PA system of FIG. 6. The two end portions of thematching module, a first port 1401 and a second port 1402, are used toimplement the matching module in the PA system to have the first port1401 for inputting the signals and the second port 1402 for outputtingthe signals or to have the first port 1401 for outputting the signalsand the second port 1402 for inputting the signals. This matching moduleincludes a first CRLH portion 1404, denoted by CRLH1 in the figure,which is coupled in series with the signal path, and a second CRLHportion 1408, denoted by CRLH2 in the figure, coupled in shunt to thesignal path at one end and having the other end 1412 either ground orshort.

Based on the phase-versus-frequency relationship for CRLH structures, asplotted in FIG. 13, the first CRLH portion 1404, CRLH1, and the secondCRLH portion 1408, CRLH2, can be designed to have two or more phasescorresponding to two or more frequencies, respectively. In the exampleof FIG. 14, the first CRLH portion 1404, CRLH1, is designed to havethree different phases ϕ₁, ϕ₂ and ϕ₃ corresponding to f₁, f₂ and f₃,which represents three different bands, band 1 and band 2 and band 3.Similarly, in this example, the second CRLH portion 1408, CRLH2, isdesigned to have three different phases ϕ′₁, ϕ′₂, and ϕ′₃, correspondingto f₁, f₂ and f₃. Therefore, the phases ϕ₁ and ϕ′₁ provide the optimumimpedance for the band 1; the phases ϕ₂ and ϕ′₂ provide the optimumimpedance for the band 2; and the phases ϕ₃ and ϕ′₃ provide the optimumimpedance for the band 3. Although this example shows the case of threebands, each CRLH portion can be designed to have two or more phasescorresponding to two or more frequency bands, based on the non-linearphase-versus-frequency curve for CRLH structures. The impedance can befurther adjusted by including one or more tunable components in each ofthe CRLH portions, which can be controlled by the controller in the PAsystem.

More than one CRLH portion can be used for the series part as well asfor the shunt part. FIG. 15 illustrates a fifth example of the matchingmodule that can be implemented in the PA system of FIG. 6. This matchingmodule includes a first set of CRLH portions 1504 and 1506, denoted byCRLH1 and CRLH2 in the figure, respectively, which are coupled inparallel, and a second set of CRLH portions 1508 and 1510, denoted byCRLH3 and CRLH4 in the figure, respectively, which are coupled inseries. Although two CRLH portions are used in each of the first set andthe second set in this example, the number of CRLH portions can bedifferent depending on the number of frequency bands, sizeconsiderations and other factors. The first set is coupled in serieswith the signal path by connecting one end of each of the CRLH portionsto the signal path and the other end of each of the CRLH portions to aswitch 1512. The two CRLH portions 1508 and 1510 in the second set arecoupled alternately in series with a switch 1512 in between to form ashunt stub, which is coupled in shunt with the signal path by having oneend connected to the signal path and the other end 1514 being eitherground or open.

By designing the CRLH1 and CRLH 2 differently to have differentphase-versus-frequency curves, the first set can be configured toprovide multiple phases corresponding to multiple frequency bands. Forexample, the CRLH portion 1504, CRLH1, can be designed to have threedifferent phases ϕ₁, ϕ₂ and ϕ₃ corresponding to f₁, f₂ and f₃, whichrepresents three different bands, band 1 and band 2 and band 3, and theCRLH portion 1506, CRLH2, can be designed to have another threedifferent phases ϕ₄, ϕ₅ and ϕ₆ corresponding to f₄, f₅ and f₆, whichrepresents another three different bands, band 4 and band 5 and band 6.The controller in the PA system can control the switch 1512 to selectthe first CRLH portion, CRLH1, for the band 1, band 2 and band3, and thesecond CTLH portion, CRLH2, for the band 4, band 5 and band 6.Similarly, the CRLH portion 1508, CRLH3, can be designed to have threedifferent phases ϕ′₁, 0′₂ and ϕ′₃ corresponding to f₁, f₂ and f₃.Furthermore, by tuning on the switch 1514 the two shunt CRLH portions1508 and 1510, CRLH3 and CRLH5, together can be designed to have anotherthree different phases ϕ′₄, ϕ′₅ and ϕ′₆ corresponding to f₄, f₅ and f₆.As a result, this specific example can provide the optimum impedance foreach of the six bands, by having ϕ₁ and ϕ′₁ for the band 1, ϕ₂ and ϕ′₂for the band 2, ϕ₃ and ϕ′₃ for the band 3, ϕ₄ and ϕ′₄ for the band 4, ϕ₅and ϕ′₅ for the band 5, and ϕ₆ and ϕ′₆ for the band 6. As noted earlier,each CRLH portion can be designed to have two or more phasescorresponding to two or more frequency bands, based on the non-linearphase-versus-frequency curve for CRLH structures. The impedance can befurther adjusted by including one or more tunable components in each ofthe CRLH portions, which can be controlled by the controller in the PAsystem.

FIG. 16 illustrates a sixth example of the matching module that can beimplemented in the PA system of FIG. 6. This matching module includesCRLH portions 1608 and 1610, CRLH3 and CRLH4, coupled in parallel toconfigure the shunt part instead of having the CRLH portions in serieswith a switch as in the previous example of FIG. 15. One end of eachCRLH portion is connected to a switch 1612, and the other end 1614 or1616 can be either ground or short. The CRLH portion 1610, CRLH4, isdesigned to provide three different phases ϕ′₄, ϕ′₅ and ϕ′₆corresponding the band 4 and band 5 and band 6, which are provided bythe series combination of the CRLH portions 1508 and 1510 in theprevious example of FIG. 15. The controller in the PA system controlsthe switch 1612 to select the CRLH 1608, CRLH3, for the band 1, band 2and band 3, and the CRLH 1610, CRLH4, for the band 4, band 5 and band 6.The series part having CRLH1 and CRLH2 is configured similarly to theexample of FIG. 15. As a result, this specific example can provide theoptimum impedance for each of the six bands, by having ϕ₁ and ϕ′₁ forthe band 1, ϕ₂ and ϕ′₂ for the band 2, ϕ₃ and ϕ′₃ for the band 3, ϕ₄ andϕ′₄ for the band 4, ϕ₅ and ϕ′₅ for the band 5, and ϕ₆ and ϕ′₆ for theband 6. As noted earlier, each CRLH portion can be designed to have twoor more phases corresponding to two or more frequency bands, based onthe non-linear phase-versus-frequency curve for CRLH structures. Theimpedance can be further adjusted by including one or more tunablecomponents in each of the CRLH portions, which can be controlled by thecontroller in the PA system. The number of CRLH portions in the shuntpart as well as in the series part can vary depending on applications.

Turning back to FIG. 4, part of the front end module 400 having the PAsystem 412, the Tx filter system 416 and the corresponding signal pathcan be viewed as an independent Tx module, which plays a major role inadjusting perturbed properties as described above. Multiple Tx modulescan be used for a wider range of applications. FIG. 17 illustrates afirst example of a Tx system including two or more Tx modules 1704, 1705. . . and 1706 coupled to input ports 1708, 1709 . . . and 1710,respectively. There are m number of the Tx modules and the respective mnumber of the input ports. Each of the Tx modules includes a PA systemand a filter system, as indicated by PA1 and F1, PA2 and F2 . . . andPAm and Fm in the figure. A controller 1712 is coupled to each of the Txmodules through a bidirectional control line 1716. In the example shownin FIG. 17, the controller is coupled to control the PA system and thefilter system in each of the Tx modules. The Tx system can includemultiple antennas 1720, 1721 . . . and 1722 coupled to the multiple Txmodules 1704, 1705 . . . and 1706, respectively, as illustrated in FIG.17. In another configuration, the Tx system can include a single antennacoupled to the multiple Tx modules. FIG. 18 illustrates a second exampleof a Tx system including two or more Tx modules 1804, 1805 . . . and1806 coupled to input ports 1808, 1809 . . . and 1810, respectively,wherein a single antenna 1820 is coupled to the Tx modules 1804, 1805 .. . and 1806. Each of the antennas 1720, 1721 . . . and 1722 is coupledto the controller 1712 in the first example of FIG. 17, and similarlythe single antenna 1820 in the second example of FIG. 18 is coupled tothe controller 1812. One or more of the plurality of antennas 1720, 1721. . . 1722 in the first example may be tunable antennas that arecontrolled by the controller 1712 to adjust the properties associatedwith the signals. Similarly, the antenna 1810 in the second example maybe a tunable antenna that is controlled by the controller 1812 to adjustthe properties associated with the signals.

In both the first example and the second example, the controller isconfigured to receive information on the signals and conditions and tocontrol each of the Tx modules to process the signals corresponding to afrequency band selected from the plurality of frequency bands, a modeselected from the plurality of modes and the conditions during a timeinterval. Further, the controller controls each of the Tx modulesvariably with time as the information varies to meet specifications onproperties associated with the signals during each time interval. Forexample, the information may include selection of the mode and thefrequency band of the signals when the user enters a foreign country.Accordingly, the controller controls each of the Tx modules to meet thespecifications on the properties associated with the signals in the modeand in the frequency band. In another example, the information mayinclude a change in the conditions such as a change in distance to abase station. Accordingly, the controller controls each of the Txmodules to have less output power than nominal output power when thedistance is shorter than a nominal distance and more output power thanthe nominal output power when the distance is longer than the nominaldistance. In yet another example, the information may include changes inthe conditions caused by a head, a hand, a metal object or otherinterference-causing objects placed in the proximity of the antenna,which can affect the signal properties by causing detuning such as ashift in frequency and/or impedance change. Based on the information,the controller controls each of the Tx modules to provide the frequencyband and/or an impedance value corresponding to the frequency band andthe conditions during the time interval. In the Tx system havingmultiple Tx modules as in the first example and the second example, twoor more of the Tx modules may process signals in the same band and thesame mode or in different bands and different modes at the same time.Thus, it is possible to process two types of signals at the same time,for example, by configuring one of the Tx modules to process voicesignals and another one of the Tx modules to process data signals.

For the case of having multiple antennas as in the first example of FIG.17, certain changes in the conditions affecting one of the multipleantennas may also have effects on the other antennas due to interactionsamong the antennas. Because of the limited space in handsets, forexample, coupling between antennas is likely to occur; therefore, it isnecessary to tune all the branches as a full system. For example,detuning caused by a heads, a hand or other interference-causing objectsplaced in the proximity of one antenna can affect the other antennas aswell. In such a complex case, the controller controls each of the Txmodules iteratively to meet the specifications on the propertiesassociated with the signals in the mode and in the frequency band. Inthis case, the PA system in each of the Tx modules is controlled tofollow the process illustrated in FIG. 8 iteratively until theproperties of signals outputting from each Tx module meet thespecifications as a full system.

What is claimed is:
 1. A communication system configured to operate fora plurality of modes and a plurality of frequency bands, comprising: anantenna configured to receive (Rx) signals or transmit out transmit (Tx)signals in a mode selected from the plurality of modes and in afrequency band selected from the plurality of frequency bands during atime interval; a switch coupled to the antenna; an input port forinputting the Tx signals; an output port for outputting the Rx signals;a Tx section coupled to the input port and the switch, the Tx sectionbeing configured to receive the Tx signals from the input port, processthe Tx signals and send the Tx signals to the switch, the Tx sectioncomprising a power amplifier (PA) system that is configured to amplifythe Tx signals; an Rx section coupled to the output port and the switch,the Rx section being configured to receive the Rx signals from theswitch, process the Rx signals and send the Rx signals to the outputport; and a controller coupled to the Tx section and the antenna througha bidirectional control line, the controller being configured to receiveinformation on the Tx signals and to control the Tx section to processthe Tx signals corresponding to the frequency band, and the mode duringthe time interval, wherein the controller configured to controls the Txsection variably with time as the information varies during each timeinterval; wherein the PA system comprises: a plurality of amplifyingmodules, each amplifying module comprising a plurality of banks, eachbank comprising plurality of transistors, wherein each bank isconfigured to have an input terminal and amplify power of signals to apredetermined level, wherein a first bank of the plurality of banks ofone of the plurality of amplifying modules comprises a first number oftransistors and a second bank of the plurality of banks of the one ofthe plurality of amplifying modules comprises a second number oftransistors different from the first number of transistors; a pluralityof matching modules, each matching module being configured to beadjusted to provide an impedance corresponding to the frequency band andthe conditions, wherein based on the information the controller isconfigured to control the input terminal of each bank to select one bankfrom each amplifying module in a predetermined series to turn on theselected banks in the series and to adjust the plurality of matchingmodules, and wherein the controller is configured to control the inputterminal of each bank and to adjust the matching modules variably withtime as the information varies to provide a signal path that has theselected banks and the adjusted matching modules during each timeinterval.
 2. The communication system of claim 1, wherein the antenna isa tunable antenna that is configured to be controlled by the controllerto adjust one or more properties associated with the Tx signals.
 3. Thecommunication system of claim 1, wherein the controller is coupled tothe PA system, the antenna, a filter system, a transceiver, a CPU, anapplication CPU, and a baseband.
 4. The communication system of claim 3,wherein the controller resides in the CPU, the application CPU or thebaseband.
 5. The communication system of claim 1, wherein theinformation includes selection of the mode and the frequency band duringthe time interval, and based on the information the controller isconfigured to control the Tx section in the mode and in the frequencyband during the time interval.
 6. The communication system of claim 1,wherein the information includes a change in distance to a base station,and based on the information the controller is configured to control theTx section to have less output power than nominal output power when thedistance is shorter than a nominal distance and more output power thanthe nominal output power when the distance is longer than the nominaldistance.
 7. The communication system of claim 1, wherein theinformation includes changes in the conditions caused by a head, a hand,a metal object or other interference-causing objects placed in proximityof the antenna.
 8. The communication system of claim 1, wherein theinformation includes changes in the conditions causing a shift infrequency, and based on the information the controller is configured tocontrol the Tx section to provide the frequency band during the timeinterval.
 9. The communication system of claim 1, wherein theinformation includes changes in the conditions causing a shift inimpedance for the Tx signals, and based on the information thecontroller is configured to control the Tx section to provide animpedance corresponding to the frequency band and the conditions duringthe time interval.